The present invention relates to graphics terminals and particularly to graphics terminals providing the user with the ability to alter the apparent viewing direction of a display derived from locally stored data.
In a graphics terminal device, pictorial information can be displayed in two dimensions with the operator being given limited control over the arrangement of the viewed information. Thus, in my prior U.S. Pat. No. 4,532,605, a zoom feature is described wherein graphics instructions are received from a host computer and stored in local memory. For providing the zoom capability different scale factor transforms are applied to the conversion of the instructions into a representation in a pixel bit map memory.
Computer graphics information can also be given for the three dimensional case, but a two dimensional cathode ray tube screen is not usually capable of making use of the information. Although a number of different directional views may be calculated in a host computer and presented separately to a terminal, ordinarily a limited number of different views of the 3D information are possible and require appreciable time for recalculation and retransmission to the terminal. Other systems are available that recalculate a graphics image for each viewing frame, allowing considerable flexibility in movement of the image, but these systems are complex and expensive.